@12V: The GPU core temperature was close to the stock cooler's result, but
quieter by 3~4 dB. VRM cooling was a massive 30°C worse, due primarily to
the location of the fan. The HD 4890 stock heatsink has a clear advantage as
its fan blows directly over the voltage regulators. The generated noise was
loud, whiny and turbulent.

@9V: Core and VRM temperatures increased by 7°C and 12°C respectively.
At 9V the pitch of the fan lowered, producing a prominentt hum and a slight
rattle, though only up close. At 1m it sounded fairly smooth though measuring
20 dBA, it was louder than we would've liked.

@7V: Temperatures continued to increase, with the GPU core heating up an additional
5°C and the VRMs approaching 150°C. Acoustically, most of the fan's
more troublesome characteristics disappear, leaving only a low pitched hum,
and at 18 dBA it can be considered quiet.

The cooler is more than capable of dealing with the GPU core of the HD 4890,
but without direct airflow over the voltage regulators, VRM temperatures soar,
especially when airflow is limited. The included fan controller allows the speed
to be adjusted from 1270 to 2410 RPM, which is approximately equivalent to 5V~12V,
but we wouldn't use it under 9V on a HD 4870/4890.

Core temperatures in the 90°C range may seem high, but it should be noted
that more impressive, dual fan coolers don't perform particularly well on the
blistering hot HD 4890 either. At the 20 dBA level (+/- 1 dB), the CoolMaxx
matches the Scythe Musashi in core temperature, and beats the Accelero S1 (with
two 100mm Scythe fans strapped to it) by 4°C. Having a second fan definitely
has its advantages however, with both the Musashi and S1 posting a whopping
20°C lead in average VRM temperature over the CoolMaxx.

As far as single fan GPU coolers go, the CoolMaxx is formidable, besting the
heavier, all-copper Zalman VF1000 by 10°C in core temperature.